The present invention relates generally to vent pipe and more specifically, but not by way of limitation, to a tab-lock fastener for interlocking vent pipe sections.
Vent pipes and chimneys are commonly found in homes to vent the products of combustion to the atmosphere. Home appliances such as space heaters, decorative fireplaces, hot water heaters, and wood-burning stoves typically include vent pipes. The vent pipes are usually made from a ductile material, such as sheet metal, and are assembled in place and installed to custom fit the vent pipe to a given space. Vent pipes are usually located between walls, in attics and in crawl spaces where there is little room to work. As a result, the manipulation of the vent pipes is difficult, particularly with regard to connecting vent pipe sections.
Over the years, local regulatory codes have also become more stringent regarding the sealing of the vent pipes to prevent leaking of the gaseous combustion products into a living space and to generally improve energy efficiency. Accordingly, the connection between adjoining sections of vent pipe must be secure to avoid venting combustion products to the living space.
There have been devices for connecting adjoining sections of vent pipe. For example, U.S. Pat. No. 4,874,191 issued to Green teaches a flue gas conduit connector for joining together ends of lengths of flue gas conduit. The lengths are locked by means of locking tabs on the outer surface of one of the flue gas conduits. The tab is bent over a locking ring on the other flue gas conduit. The two ends are provided with complementary taper joints and a sealing gasket to provide a leak-proof flue passage.
While functional, the vent pipe connectors taught by Green U.S. Pat. No. 4,874,191, and by others, can be time-consuming and cumbersome to install. In the past, some vent pipe installers have used sheet metal screws to secure vent pipe joints. Although this practice is not widely accepted, some installers have adopted it as a necessary measure to ensure that vent pipe joints will not part accidentally during other stages of construction. For example, a vent pipe can be subjected to accidental disassembly when a termination cap located at the top of a gas vent pipe assembly is removed to allow installation of roofing materials, such as shingles and flashings.
When inserting sheet metal screws into vent pipe joints, an installer must use tools and sheet metal screws that are not supplied with the vent pipe. Another drawback occurs when using sheet metal screws with a double-wall vent pipe, such as a B-vent. A B-vent is a double-wall vent pipe that typically has a sheet metal outer wall and an aluminum inner wall, and an installer can accidentally drive a sheet metal screw through both the outer and inner walls of the assembly. Penetration of the inner wall is usually unacceptable and requires the installer to remove and reinstall the B-vent. Additionally, the use of sheet metal screws can result in an undesirable, audible ticking noise during the heating and cooling cycles of the gas vent under normal use. This ticking noise is caused by the sheet metal screw being positioned next to, and contacting, the aluminum inner wall of the gas vent pipe.
There exists a need for a connector to join vent pipe sections that is easy to work with, that can be quickly installed, and that maintains the structural integrity of the vent pipe sections.
The present invention is directed to a tab-lock fastener for vent pipe for connecting vent pipe sections such as is typically used to exhaust combustion products of natural gas appliances. The tab-lock fastener includes an locking tab formed on female end of a first vent pipe section and a guide groove formed on a male end of a second vent pipe section; also, a locking tab is provided on the female end of the first vent pipe section. The first and second vent pipe sections are assembled by inserting the male end of the first vent pipe section into the female end of the second vent pipe section, the vent pipe sections aligned so that the locking tab of the first vent pipe section is disposed to be in the guide groove of the second vent pipe section. The vent pipe sections are then rotated relative one to the other so that the locking tab is aligned over a tab-lock receptacle formed in the male end of the second vent pipe section. The vent pipe sections are interlocked by bending the locking tab to engage a wall of the tab-lock receptacle to prevent unwanted disconnection of the first vent pipe section from the second vent pipe section.
The features and advantages of the present invention will become apparent upon reading the following detailed description along with the associated drawings and the appended claims.